THE SLAVE TRENCHES OF HAKOTEP page 10 wrote:
The shadow cast by the Five-Pointed Sun on the city
below is unusually dark and cold. Within this area of
darkness, the shadow creates a region of desecration, as
the desecrate spell. This effect extends into the pyramid’s
interior as well, though inside the Five-Pointed Sun the
effect functions as if in the presence of an evil altar. (Hit
points and other adjustments to attacks, damage, and saving
throws for undead creatures are included as appropriate in
their statistics.) This desecrate effect functions at CL 15th,
and if targeted via dispel magic, it automatically reactivates
after 1d4 rounds as long as Isatemkhebet exists.
With the desecrate in mind, te damage shown in the book is correct.
Anyway in this post I found some erratas in Isatemkhebet stat block. You can check it if you want.